Delayed return pressure actuated device



April 12, 1966 A. P. ZASKE ETAL 3,246,094

DELAYED RETURN PRESSURE ACTUATED DEVICE Filed Dec. 15, 1963 HIMHINVENTORS ATTOR/Vf) United States Patent 3,246,094 DELAYED RETURNPRESSURE ACTUATED DEVICE Arthur P. Zaske, Utica, and Gordon G. Gast,Madison Heights, Mich, assignors to Holley Carburetor Compauy, Warren,Mich, a corporation of Michigan Fiied Dec. 13, 1963, Ser. No. 330,322 4Claims. (Cl. 200-83) This invention relates generally to pressureresponsive devices, and more particularly to a type of switch which isactuated upon an increase in hydraulic or pneumatic pressure and whichremains actuated for a predetermined length of time after the pressuresubsides.

There are numerous applications wherein it would be advantageous tooperate an electric motor by such a switch. For example, a switch ofthis type is included in the parent application mentioned above whereina waste treatment system is described and illustrated.

Therefore, a general object of the invention is to provide an improvedpressure-responsive device.

A more specific object of the invention is to provide such a switchwhich will be actuated immediately once an increase in operatingpressure occurs, and which includes means for maintaining the switchclosed for a predetermined length of time after the pressure hassubsided.

A further object of the invention is to provide such a switch which iseconomical to manufacture, easy to assemble, compact in form andeflicient in operation.

Other objects and advantages of the invention will become more apparentwhen reference is made to the following drawing wherein:

FIGURE 1 is a cross-sectional view of a switch embodying the invention;and

FIGURE 2 is a fragmentary cross-sectional View taken along the plane ofline 22 of FIGURE 1 and looking in the direction of the arrows.

Referring to the drawings in greater detail, the pressure responsiveswitch assembly of FIGURE 1 includes two diaphragrns 12 and 14 confinedagainst the opposite sides of a body portion 16 by a cover 18 and a ring20, respectively. The cover 18 may either be attached to or form a partof the housing 21 containing a chamber 22 which is subjected to changesin hydraulic or pneumatic pressures.

The ring may be fastened to the body portion 16, and the body portion16, in turn, fastened to the cover 18 as by screws 23. As usual, each ofthe diaphragms 12 and 14 is preferably supported by a pair of washers 24and 26 positioned on the opposite sides thereof, and fastened together'by rivets 28 and 30.

The two diaphragms 12 and 14 thus form oppositely disposed chambers 32and 34 with the annular cavities 36 and 38 formed in the body portion16. The body portion 16 has formed therein a central passageway havingtwo diameters 40 and 42 and an ofl-center passage 44 communicatingbetween the two chambers 32 and 34, passage 44 including a calibratedrestriction 45. A spring 46, restrained at its one end by a springretainer 48 fixed in body 16 urges a valve 50 against the seat 52 formedat the junction of the two diameters 40 and 42 of the central passage.The spring retainer 48 includes a plurality of ports 54. Internal stops56 and 58 may be cast or otherwise formed on the body portion 16 tolimit the downward and upward movements of the upper and lowerdiaphragms 12 and 14, respectively.

A bottom cover 60 formed with a cavity 62 is fastened to the bodyportion 16 with the ring 20 confined therebetween so as to form thechamber 64 beneath the diaphragm 14. The chamber 64 contains a pair ofelec- 3,246,094 Patented Apr. 12, 1966 trical contacts 66 and 68, theformer being aflixed to the bottom cover 60. The other contact 68 isfixedly attached to the free end 70 of a flexible strip or blade 72, theother end 74 of which is secured in the wall 76 of the cover 60. Wireleads 78 are fixed in any suitable manner to the fixed contact 66 andthe mounted end 74 to the blade 72. The blade 72 extends through or isotherwise fixed to the collar 80 of a vertically movable rod 82positioned directly below the center of the diaphragm 14 and adapted tofit, at its upper end, into a retainer 84 attached to the rivet 36.

A cap 86 formed with an atmospheric bleed 88 is fastened to a hollowcylindrical extension 90 which may be formed on the cover 60, thusforming a chamber 92 containing a spring 94. The spring 94 is confinedbetween lower and upper spring seats 96 and 98, the location of thelower stationary seat 96 being manually adjustable, as by an adjustingscrew 100, and the upper movable seat 98 being at all times abuttedagainst the rod 82, which extends through an opening 102 in the wall104.

An additional annular chamber 106 is formed between the cover 18 and theupper diaphragm 12. As illustrated in FIGURE 2, a plurality ofpassageways 108, 169 and 110, a junction of which may be fitted with ascreen or porous filter 112, provide communication between the pressuresource 22 and the chamber 106. If desired, the passageways 108, 109 and110 may be replaced by a single opening in the top face of the cover 18.In either event, the passageways or the opening must communicate with asource 22 of hydraulic or pneumatic pressure.

The wire leads 78 connect between a motor (not shown) and a power supply(not shown) through the motor switch assembly 10 so that the motoroperates when the contacts 66 and 68 are closed.

That portion of the motor switch assembly which is confined between thediaphragms 12 and 14 is a completely enclosed, fluid-filled system.Depression of the diaphragm 12 by the pressure, which has increased inthe upper chamber 166 via the passageways 108, 109 and 110, will forcethe lower diaphragm 14 downwardly by virtue of the fluid being shiftedfrom the chamber 32 to the chamber 34 through the central passageways 42and 48, i.e., past the spring loaded valve 50 and through the ports 54.The downward movement of diaphragm 12 will continue until the innerwasher 26 of the diaphragm 12 abuts against the stops 56. Since spring94 maintains member 84 in contact with rod 82, the associated downwardmovement of the lower diaphragm 14 results in movement of the movablecontact 68 fixed on the end of the blade 72 downwardly into contact withthe stationary contact 66, thereby completin the circuit through theloads 78 which connect with the electric motor.

It may be highly desirable that the operation of the motor continue fora predetermined length of time, say 8 to 30 seconds, after the pressurein the upper chamber 106 subsides. This is accomplished by the fact thatthe fluid in the chamber 34 must return to the chamber 32 through thecalibrated restriction 45 when the downward flow of fluid has ceased dueto the relaxation of pressure in chamber 106 and the valve 50 is againmoved against the seat 52 by the spring 46. Calibration of therestriction 45 will, of course, determine the length of time requiredfor this transfer of the fluid, and thus the time that the operation ofthe motor continues. Once the pressure in chamber 106 subsides, theupward movement of the lower diaphragm 14 toward the stops 58 will beeffected by the spring 94, which raises the rod 82, and hence thediaphragm 14,, against the dashpot effect of the calibrated restriction45 between the chambers 32 and 34. After the predetermined length oftime, when sufficient fluid has been displaced through the calibratedrestriction 45, the movable contact 68 would, of course,

have been raised off the stationary contact 66, thereby breaking thecircuit and stopping the motor.

Since the blade 72 on which the movable contact :53 is mounted is bentdownwardly where it engages the stem 82, additional switch opening delaycan be provided if the travel of the stem 82 is suificient to straightenthe blade upon closing of the switch. Inotherwords,the blade uponclosing the of switch. In other words, the blade will first have to bereturned to its free bent position before further upward travel of thestem 82 opens the contacts. The delay is, of course, also aiiected bythe size of the restriction 45 and the force of the spring $4.

The adjustment 1% for the spring 34 is provided to compensate for apressure head in chamber 1% which might constitute an influence on thesystem. It is desirable that the switch be responsive to the rise inpressure in the chamber 166 resulting from some cause other than thehead pressure. The adjustment 1% is thus employed to vary the pre-loadof the spring 94 depending upon the above mentioned head. It isapparent, however, that the setting of the member 100 may also beutilized simply to afiect the duration of operation of the motor.

From the above description, it should be apparent that the inventionprovides an apparatus 1!) which may be used in any application requiringthat a switch or other mechanism, such as a valve for example, beactuated as soon as the diaphragm 12 senses a predetermined increase inpressure and wherein the mechanism must remain actuated for apredetermined length of time after the pressure build-up in the chambers22 and 106 has subsided.

While but one modification of the invention has been illustrated anddescribed, other modifications may, of course, be possible within thescope of the appended claims. 1

What we claim as our invention is:

1. A device adapted to be actuated upon an increase in fluid pressureand to remain actuated for a predetermined time after the actuatingpressure subsides, said device comprising an intermediate body havingoppositely disposed cavities formed therein so as to provide anintermediate rigid Wall, a first movable diaphragm secured to one end ofsaid body by means of a first end cover having a recess formed thereinso as to provide a first chamber between said rigid Wall and said firstdiaphragm and a second chamber between said first diaphragm and saidfirst end cover, a second movable diaphragm secured to the other end ofsaid body by means of a second end cover member having a recess formedtherein so as to provide a third chamber between said rigid wall andsaid second diaphragm and a fourth chamber between said second diaphragmand said second end cover, a source of varying fluid pressure outsidesaid first end cover, a passage through said first end cover membercommunicating said varying pressure to said second chamber, atwodiameter passageway formed in said rigid wall for providingcommunication between said first chamber and said third chamber, thesmaller diameter of said passage serving as a valve seat, aspring-loaded valve in the larger diameter portion of said two-diameterpassage normally preventing communication between said first and thirdchambers, a continuously open calibrated restriction formed in saidrigid wall providing continuous communication between said first andsaid third chamber, said first and third chambers containing trappedfluid such that when said first diaphragm is actuated by an increase insaid varying pressure and a predetermined pressure in said first chamberis attained said trapped fluid is transferred past said valve and tosaid third chamber so as to actuate said second diaphragm in the samedirection that said first diaphragm was actuated, a stem member attachedto said second diaphragm and extending into said fourth chamber, switchmeans connected to said stem member and means operatively connected tosaid stem member for returning said second diaphragm to its originalposition when said varying pressure subsides, the return of said fluidfrom said third chamber to said first chamber being retarded by theclosing of said valve so as to cause said fluid to return through saidrestriction.

2. A pressure-responsive electric switch comprising a pair of pressureresponsive devices, first and second chambers positioned between saidwall and said pressure responsive devices, said two chambers containinga fluid, a first cover including a first recess, said first recessserving as a third chamber with one of said pressure responsive devices,a passageway in said first cover, a second cover including a secondrecess, said second recess serving as a fourth chamber with the other ofsaid pressure responsive devices, said wall having annuli formed on bothsides thereof for confining said pressure responsive devices againstsaid first and second covers, a two-diameter passageway formed throughsaid wall, said smaller diameter portion serving as a valve seat, aspring retainer fixedly attached adjacent the larger diameter opening, apiuraiity of orifices formed in said spring retainer, a valve located insaid larger diameter portion of said passageway, a first spring confinedbetween said spring retainer and said valve for urging said valve towardsaid valve seat, a fixed restriction formed through said intermediatewall for continual communication between said two chambers, a stemfixedly attached to one of said pair of presstem, a first contactmounted on the free end of said flexible blade, a second contact fixedlyattached to said second cover adjacent said first contact, a manuallyadjustable spring retainer, a movable spring retainer, and a secondspring confined between said manually adjustable retainer and saidmovable retainer, said movable spring retainer being urged against saidstem by said second spring.

3. A switch as described in claim 2 wherein said intermediate wallincludes stops formed on both sides thereof limiting the travel of eachof said pair of pressure respon sive devices.

A switch as described in ciaim 2 wherein said passageway formed in saidfirst cover includes a filter element confined therein.

References Cited by the Examiner UNITED STATES PATENTS 2,350,938 6/1944Sparrow 20083 X 2,389,856 11/1945 Jones 200-34 2,777,028 1/1957 Kendallet al. 2()O83.2 3,055,994 9/1962 Lundeen -2 20034 X BERNARD A. GILHEANY,Primary Examiner.

HARRY M. FLECK, 111., Assistant Examiner,

1. A DEVICE ADAPTED TO BE ACTUATED UPON AN INCREASE IN FLUID PRESSUREAND TO REMAIN ACTUATED FOR A PREDETERMINED TIME AFTER THE ACTUATINGPRESSURE SUBSIDES, SAID DEVICE COMPRISING AN INTERMEDIATE BODY HAVINGOPPOSITELY DISPOSED CAVITIES FORMED THEREIN SO AS TO PROVIDE ANINTERMEDIATE RIGID WALL, A FIRST MOVABLE DIAPHRAGM SECURED TO ONE END OFSAID BODY BY MEANS OF A FIRST END COVER HAVING A RECESS FORMED THEREINSO AS TO PROVIDE A FIRST CHAMBER BETWEEN SAID RIGID WALL AND SAID FIRSTDIAPHRAGM AND A SECOND CHAMBER BETWEEN SAID FIRST DIAPHRAGM AND SAIDFIRST END COVER, A SECOND MOVABLE DIAPHRAGM SECURED TO THE OTHER END OFSAID BODY BY MEANS OF A SECOND END COVER MEMBER HAVING A RECESS FORMEDTHEREIN SO AS TO PROVIDE A THIRD CHAMBER BETWEEN SAID RIGID WALL ANDSAID SECOND DIAPHRAGM AND A FOURTH CHAMBER BETWEEN SAID SECOND DISPHRAGMAND SAID SECOND END COVER, A SOURCE OF VARYING FLUID PRESSURE OUTSIDESAID FIRST END COVER, A PASSAGE THROUGH SAID FIRST END COVER MEMBERCOMMUNICATING SAID VARYING PRESSURE TO SAID SECOND CHAMBER, ATWODIAMETER PASSAGEWAY FORMED IN SAID RIGID WALL FOR PROVIDINGCOMMUNICATION BETWEEN SAID FIRST AND THIRD SAID THIRD CHAMBER, THESMALLER DIAMETER OF SAID PASSAGE SERVING AS A VALVE SEAT, ASPRING-LOADED VALVE IN THE LARGER DIAMETER PORTION OF SAID TWO-DIAMETERPASSAGE NORMALLY PREVENTING COMMUNICATION BETWEEN SAID FIRST AND THIRDCHAMBERS, A CONTINUOUSLY OPEN CALIBRATED RESTRICTION FORMED IN SAIDRIGID WALL PROVIDING CONTINUOUS COMMUNICATION BETWEEN SAID FIRST ANDSAID THIRD CHAMBER, SAID FIRST AND THIRD CHAMBERS CONTAINING TRAPPEDFLUID SUCH THAT WHEN SAID FIRST DIAPHRAGM IS ACTUATED BY AN INCREASE INSAID VARYING PRESSURE AND A PREDETERMINED PRESSURE IN SAID FIRST CHAMBERIS ATTAINED SAID TRAPPPED FLUID IS TRANSFERRED PAST SAID VALVE AND TOSAID THIRD CHAMBER SO AS TO ACTUATE SAID SECOND DIAPHRAGM AND EXTENDINGINTO SAID SAID FIRST DIAPHRAGM WAS ACTUATED, A STEM MEMBER ATTACHED TOSAID SECOND DIAPHRAGM AND EXTENDING INTO SAID FOURTH CHAMBER, SWITCHMEANS CONNECTED TO SAID STEM MEMBER AND MEANS OPERATIVELY CONNECTED TOSAID STEM MEMBER FOR RETURNING SAID SECOND DIAPHRAGM TO ITS ORIGINALPOSITION WHEN SAID VARYING PRESSURE SUBSIDES, THE RETURN OF SAID FLUIDFROM SAID THIRD CHAMBER TO SAID FIRST CHAMBER BEING RETARDED BY THECLOSING OF SAID VALVE SO AS TO CAUSE SAID FLUID TO RETURN THROUGH SAIDRESTRICTION.